main()
{
    int a, i, b, n;
    printf("There are following friendly - numbers pair smaller than 3000:\n");
    for(a=1; a<3000; a++)
    {
        for (b=0, i=1; i<= a/2 ; i++)
          if(! (a%i)) b+=i;
        for (n=0, i=1; i<= b/2 ; i++)
          if(! (b%i)) n+=i;
        if (n==a && a<b)
          printf(" %4d.. %4d",a,b);
    }
}